A selective effect of somatostatin (SRIF) on the in vitro release of alanine and glutamine has been observed in skeletal muscle. The mechanism of this selective action will be investigated. The effect of marcaine (bupivacaine) on the in vitro release of amino acids from skeletal muscle will be studied. The mechanism of glutamine utilization by human diploid fibroblasts during different cycles of cell growth will be investigated. Studies on increased gluconeogenic and decreased ketogenic action of alanine on liver will be extended. These investigations provide rationale for the study of physiological and endocrine factors affecting amino acid release from muscle.